Drilling apparatus

ABSTRACT

The disclosure herein describes a drilling apparatus for tapping fluid-conveying pipes under high internal pressure and temperature. The apparatus consists of a tubular housing in which a piston supporting a core drill shaft is axially displaceable. The shaft is rotated by an air driven motor and the piston is moved under the action of a working fluid fed into the housing through appropriate hydraulic conduits. The fluid is maintained under a predetermined positive pressure to provide the core drill with a constant cutting feed. In one preferred form of the invention, the air driven motor is enclosed in the piston.

Umted States Patent [151 3,703,909 Erb 1 Nov. 28, 1972 [54] DRILLING APPARATUS v Primary Examiner-Henry T. Klinksiek I M 7 v [72] Inventor 32 23 $2223: Erb ontreal Assistant Examiner-David R. Matthews Attorney-Cushman, Darby & Cushman [73] Assignee: Hurtsteel Products Ltd., Montreal East, Quebec, Canada Filed: July 14, 1971 Appl. No.: 162,569

US. Cl ..137/318 Int. Cl. ..F16e 41/04, B23b 41/08 Field of Search 137/317, 318; 408/130; 29/157,

References Cited UNITED STATES PATENTS Klancnik ..408/130 X Clarke ..137/318 X [57] 'ABSTRACT The disclosure herein describes a drilling apparatus fortapping fluid-conveying pipes under high internal pressure and temperature. The apparatus consists of a tubular housing in which a piston supporting a core drill shaft is axially displaceable. The shaft is rotated by an air driven motor and the piston is moved under the action of a working fluid fed into the housing through appropriate hydraulic conduits. The fluid is maintained under a predetermined positive pressure to provide the core drill with a constant cutting feed. In one preferred form of the invention, the air driven motor is enclosed in the piston.

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/N VEN TOR Brian R. E R8 4 ZJMAA MgM MJQM DRILLING APPARATUS This invention relates generally to a drilling apparatus; more particularly, the invention pertains to an apparatus for drilling holes in pipes, especially those under high internal pressure and temperature.

Presently known drilling machines for tapping pipes and similar devices are operated by hand power or are 'constructed to be operated by mechanical power.

These machines are sufficiently effective when used to drill holes in water mains or similar conduits but are quite unsatisfactory when it comes to drilling holes in pipes, for example, those where their internal pressure may easily range between 500 and 3,000 psi and where their average internal temperature is about 500 F.

Furthermore, these drilling machines are not acceptable when the speed at which the holes are to be drilled is of importance. One particular aim of the present invention is to drill holes in oil well pipes or casings in order to tap them with a branch line which is then connected to a supply of fire extinguishing material. Therefore, in the event of a fire, it is evidently essential that any drilling be carried out as quickly as possible; present machines are not capable of such rapid drilling. Also, in the latter example, it is sometimes important that the line be tapped at a given angle; again, present drilling machines are not capable of drilling holes at an acute angle to the longitudinal axis of the pipe; they can only be used if the drilling force is applied at 90 to the pipe.

Yet, another disadvantage of present drilling machines is that none are capable of working underwater for the tapping of an oil well pipe located on an offshore rig.

It is an object of this invention to provide a drilling apparatus which is capable of drilling a hole through a pipe where the internal pressure and temperature are relatively high, and which is equipped with means to compensate for any pressure and temperature variations due to the piercing of such pipe.

Another object of the present invention is to provide an apparatus which is capable of drilling holes in a pipe at a relatively high speed, thereby considerably reducing the drilling time.

It is a further object of the present invention to provide a drilling apparatus which is capable of drilling holes at an acute angle to the longitudinal axis of the pipe.

The drilling apparatus of the present invention is part of a drilling assembly that further includes a tubular member which is adapted to be secured to the pipe outer wall and a gate valve which is adapted to be secured to an open end of the tubular member. The drilling apparatus comprises a hollow elongated body, having one end opened and one opposite end closed; an axially displaceable piston in the body, having a leading end and a trailing end, the trailing end forming with the closed end of the body an expansible chamber; a shaft supported in the piston and extending through the leading end thereof; a cutting head fixedly mounted on one end of the shaft; drive means for applying torque to the shaft; and hydraulic conduit means for forcing a working fluid in the expansible chamber to thereby axially displace the piston in the body; the working fluid being maintained under a predetermined positive pressure to advance the cutting head with a constant cutting feed.

In a preferred form of the invention, the drive means are enclosed within the piston; this type of drilling apparatus is quite suitable for use underwater in connec-' tion with offshore drilling.

The above and other objects of the present invention will become apparent from the following description and the accompanying drawings of exemplary forms of the invention, wherein: a

FIG. 1 is a cross-sectional view of a drilling assembly made in accordance with the present invention and shown affixed to part of a pipe;

FIG. 2 is an enlarged cross-sectional view of part of the core drill against the wall of the pipe;

FIG. 3 is a cross-sectional view taken along lines 3 3 of FIG. 1;

FIG. 4 is a cross-section of another form of the drilling assembly made in accordance with the present invention;

FIG. 5 is an enlarged cross-sectional view of the connection between the core drill and the piston;

FIG. 6 is a cross-sectional view taken along lines 6- 6 of FIG. 4;

FIG. 7 is a side elevational view of the drilling assembly shown in FIG. 4 but illustrating another form of the hydraulic system for controlling the displacement of the piston; and

FIG. 8 is a schematic view of the hydraulic system for operating the drilling apparatus represented in FIG. 7.

Corresponding reference characters indicate corresponding or like parts throughout the several views of the drawings.

Referring now more particularly to FIG. 1, there is shown a drilling assembly generally represented by numeral 10 for drilling holes into a pipe 12, especially those having a fluid therein under high pressure and temperature. An example of such pipes is the oil well pipe which encloses oil and/or gas having a pressure which may, in some cases, reach 3,000 psi. The drilling assembly 10 consists of a first tubular member 14 which has one end welded or otherwise attached to the pipe 12 and the other end sealingly connected to a conventional gate valve 16 having a gate 18. Attached to the inlet of the gate valve 16 is a drilling apparatus 20.

This drilling apparatus comprises a sleeve housing 22 which is seal-tight at its inlet section 23 and which receives therein a piston 24 which is capable of axial displacement in the housing 22 as well as in the hollow portion of the gate valve 16 and of the tubular member 1 4. Gate valve 16 is refined to also form a piston housing to allow piston 24 to travel through the gate valve without loss of hydraulic fluid: the gate valve thus becomes an extended part of the sleeve housing with the same qualities and inside dimensions. Piston 24 supports centrally thereof a shaft 26 which has its leading end threaded to a core drill 28 and its other end extending outside the drilling apparatus and connected to a motor (not shown) for rotating the shaft. The rotation of the piston by the shaft is avoided by means of a conventional ball bearing arrangement 30 (see FIG. 3).

The core drill 28 consists of an annular head portion 32 which is fixedly secured to a rigid hollow member 34 bolted, such as shown at 36, or otherwise secured to member 38 threadedly engaged to the shaft 26. Member 32 is made of an abrasive material; however, due to the high rotational speed required, a diamond head or a head made of a cemented carbide, such as the one known under trademark Carboloy, could be used. Furthermore, one of the main uses of the drilling assembly made in accordance with the present invention is for drilling holes at an angle to a pipe line; the cut piece 40 (see FIG. 2) of the pipe thus has an ovular shape. The hollow member 34 must therefore have a sufficiently long bore to receive the cut piece 40. Many known devices could be mounted in the member 34 for ensuring that the cut piece 40 is retained inside the core drill.

In operation, the core drill 28 is rotated by the motor and the piston 24 is displaced inside the housing and towards the pipe by introducing a working fluid in area 42 behind piston 24; a conduit 44 is connected to a pump (not shown) through means of a conventional manual valve 46. As the drill head 32 contacts the outside surface of pipe 12, the pressure applied on the piston by the fluid is equal to a predetermined positive pressure, i.e., a pressure slightly in excess of the pressure required for overcoming the frictional resistance of piston 24. Once the hole is drilled, the cut piece 40 is retained inside member 34 by suitable means as explain'ed above and the return of the piston to its original position isv carried out depending on the pressure inside pipe 12. If fluid is flowing through pipe 12, cutting through the wall will create a vacuum inside the drill assembly in such a case, the return of the piston can be made manually or automatically by exerting a force toward the right as shown in FIG. 1. Fluid behind the piston is thereby caused to return to its reservoir. However, if pipe 12 is capped, the pressure inside the pipe, upon drilling a hole through its wall, will cause on the piston a considerable return force. In such a case, the return of the fluid to its reservoir must be controlled to absorb the return of the piston inside the housing; such a control system will hereinbelow be described in relation to the specific form of the invention illustrated in FIG. 8 where the fluid line is provided with a manual valve and a check valve.

Referring to FIG. 4, another form of the invention is illustrated. Since one of the principal aims of the invention is to enable the tapping of an oil well pipe, it is also an object of this invention to provide a drillv assembly which will be able to cut a hole in an oil well pipe which may be located underwater, such as that used in offshore drilling.

The drill apparatus shown in FIG. 4 as 20 may be used for this purpose. This drilling apparatus includes a sleeve housing 22' which encloses a high pressure piston 24 to which is connected by means of a shaft 26 a core drill 28'. Piston 24 consists of a cylindrical housing 46 in which is received an air driven motor 48 to rotate shaft 26. Sealingly connected to the motor is a hollow conduit 50 receiving a coaxial conduit 52 for air passage to the motor while the remaining portion of the interior of conduit 50 serves as a return path for the air after being ejected from the motor. This conduit 50 may be remotely connected to a supply located on a nearby boat.

Referring more particularly to FIG. 5, the connection ofthe piston with the cutting head is illustrated. Motor 48 has at its leading end a flange 54 which is bolted to the housing 46. Shaft 26' rotatably driven by the air driven motor 48, is threadedly connected to the core drill 28'; also bolted to housing 46 and to the flange 54 is a scraper 56, the front end of which will scrape the interior wall 58 of the drilling assembly while serving as a heat shield for the protection of the motor 48 against the high temperature caused by the drilling. A conventional ball bearing arrangement 58 enables the cutting aid 28' to rotate relative to the non-' rotating scraper 56.

To prevent the motor from rotating in cases where the core drill becomes jammed, a locking mechanism 60 is provided-consisting of a bracket 62 having at its lower portion two openings to slidably receive a pair of rods 64 and 66, and having atits upper portion one larger opening to receive the air conduit 50. The other ends of rods 64 and 66 are rigidly secured to a bracket 65 fixed to the outside wall of housing 22'. v

In operation, motor 48 is driven by injecting air through conduit 50 by means of a push-pull hydraulic system, for example. Again the advance of piston 24' is effected by means of an hydraulic system. In this instance, fluid is introduced in area 67 by means of an orifice 68 provided in the wall of the sleeve housing 22'. A second orifice 70 is also provided in housing 22' for the return of the fluid when piston 24 is retracted to its original position. The orifices 68 and 70 are in communication with a pump 72 by means of conduits 74 and 76 respectively. Pump 72, connected to a reservoir 78, provides sufficient pressure to advance piston 24 toward the pipe to be drilled. The pump is regulated to ensure that a predetermined positive pressure, say 10 lbs., is constantly maintained so that the drilling operation is always progressing. Pump 72 is also regulated to ensure proper retracting of the drilling apparatus, whether or not the pressure inside the pipe line is greater or lower than the pressure inside area 42".

Referring to FIG. 7, another form of a mechanism for controlling the return of the piston to its original position is shown. In this instance, only one orifice 68' is provided in the sleeve housing 22'. A conduit 74' is received in this orifice for communication with the inside area 42 of the drilling apparatus. A cylinder 76 is mounted by means of brackets 78 and 79 to the exterior wall of the housing 22'. The cylinder includes a piston 80 and rod 82, one end of the rod being fixedly secured to the bracket 62. Two lines 84 and 86 are in communication with the interior of the cylinder at each end thereof. Line 84 is connected to a pump 88 while line 86 joins line 74 to communicate with pump 88 by means of a manual valve 90 and a check valve 92. In operation, pump 88 feeds fluid through check valve 92 in chamber 42' to thereby move piston 24' in the drilling assembly. Through the connection of bracket 62 secured to the conduit 50 and to the piston rod 82, piston 80 forces fluid inside cylinder 76 into line 84 and pump 88. When it is required to retract the piston 24' manual valve 90 is opened and the fluid inside the cylinder 76 and inside area 42 are returned to the reservoir 94 via the valve 90, line 96 and pump 88.

Although the invention has been described above in relation to specific forms of the invention, it is evident that it may be refined and modified in various ways. It is therefore wished to have it understood that the present invention is not limited in interpretation except by the terms of the following claims.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

l. A drilling apparatus comprising a hollow elongated body having one end opened and one opposite end closed; a piston'axially displaceable in said body, said piston having a leading end and a trailing end, said trailing end forming with said closed end of said body an expansible chamber; a shaft supported in said piston and extending through the leading end thereof; a cutting head fixedly mounted on one end of 'said shaft adjacent the leading end of said piston; drive means for applying torque to said shaft; and hydraulic conduit means communicating with said expansible chamber for introducing a working fluid therein to thereby axially displace said piston in said hollow body; said working fluid being maintained under a predetermined positive pressure to advance said cutting head with a constant cutting feed.

2. A drilling apparatus as defined in claim 1 wherein said cutting head includes a core drill made of a highly resistant abrasive material.

3. A drilling apparatus as defined in claim 1 wherein said cutting head includes a core drill made of a material chosen from the class including diamond and cemented carbide.

4. A drilling apparatus as defined in claim 3 wherein said cutting head includes an elongated hollow cylindrical member supporting said core drill at one end thereof.

5. A drilling apparatus as defined in claim 1 wherein said drive means are enclosed in said piston and further comprising conduit means extending through the trailing end of said piston and the closed end of said body inside said piston.

8. A drilling apparatus as defined in claim 6 further comprising securing means for fixing said air passageways to the outer wall of said hollow body to prevent relative rotation therebetween.

9. A drillingapparatus as defined in claim 8 wherein said securing means include a bracket fixed to said air passageways and rod means having one end fixed to the outer wall of said body and the other end slidably received in said bracket.

10. A drilling apparatus as defined in claim 8 wherein said securing means include a bracket fixed to said air passageways and rod means having one end fixed to said bracket and the other end secured to a piston slidably received in an hydraulic cylinder fixed to the outer wall of said hollow body, said cylinder being in fluid communication with said hydraulic conduit means. I

11. A drilling assembly for drilling holes in pipes under high internal pressure and temperature, comprising a tubular member adapted to be attached at one end thereof to a pipe to be drilled, a gate valve secured to said tubular member; a hollow elongated cylindrical body having one end connected to said gate valve and the opposite end closed; a piston axially displaceable in said body, gate valve and tubular member; said piston having a leading end and a trailing end, said trailing end forming with said closed end of said body an expansible chamber; a shaft supported in said piston and extending through the leading end thereof; a cutting head fixedly mounted on one end of said shaft adjacent the leading end of said piston; drive means for applying torque to said shaft; and hydraulic conduit means communicating with said expansible chamber for introducing a working fluid therein to thereby axially displace said piston in said hollow body; said working fluid being maintained under a predetermined positive pressure to advance said cutting head with a constant cutting attack on said pipe.

12. A drilling assembly as defined in claim 11 wherein said one end of said tubular member extends in a plane oblique relative to the longitudinal axis of said tubular member. 

1. A drilling apparatus comprising a hollow elongated body having one end opened and one opposite end closed; a piston axially displaceable in said body, said piston having a leading end and a trailing end, said trailing end forming with said closed end of said body an expansible chamber; a shaft supported in said piston and extending through the leading end thereof; a cutting head fixedly mounted on one end of said shaft adjacent the leading end of said piston; drive means for applying torque to said shaft; and hydraulic conduit means communicating with said expansible chamber for introducing a working fluid therein to thereby axially displace said piston in said hollow body; said working fluid being maintained under a predetermined positive pressure to advance said cutting head with a constant cutting feed.
 2. A drilling apparatus as defined in claim 1 wherein said cutting head includes a core drill made of a highly resistant abrasive material.
 3. A drilling apparatus as defined in claim 1 wherein said cutting head includes a core drill made of a material chosen from the class including diamond and cemented carbide.
 4. A drilling apparAtus as defined in claim 3 wherein said cutting head includes an elongated hollow cylindrical member supporting said core drill at one end thereof.
 5. A drilling apparatus as defined in claim 1 wherein said drive means are enclosed in said piston and further comprising conduit means extending through the trailing end of said piston and the closed end of said body for actuation of said drive means.
 6. A drilling apparatus as defined in claim 5 wherein said drive means is an air driven motor and said conduit means include air passageways to said air driven motor.
 7. A drilling apparatus as defined in claim 6 wherein said piston includes a scraping member fixed to the leading end thereof and adapted to contact the inside wall of said hollow body, said scraping member being made of a high-temperature resistant material and acting as a heat shield for protecting said air driven motor inside said piston.
 8. A drilling apparatus as defined in claim 6 further comprising securing means for fixing said air passageways to the outer wall of said hollow body to prevent relative rotation therebetween.
 9. A drilling apparatus as defined in claim 8 wherein said securing means include a bracket fixed to said air passageways and rod means having one end fixed to the outer wall of said body and the other end slidably received in said bracket.
 10. A drilling apparatus as defined in claim 8 wherein said securing means include a bracket fixed to said air passageways and rod means having one end fixed to said bracket and the other end secured to a piston slidably received in an hydraulic cylinder fixed to the outer wall of said hollow body, said cylinder being in fluid communication with said hydraulic conduit means.
 11. A drilling assembly for drilling holes in pipes under high internal pressure and temperature, comprising a tubular member adapted to be attached at one end thereof to a pipe to be drilled, a gate valve secured to said tubular member; a hollow elongated cylindrical body having one end connected to said gate valve and the opposite end closed; a piston axially displaceable in said body, gate valve and tubular member; said piston having a leading end and a trailing end, said trailing end forming with said closed end of said body an expansible chamber; a shaft supported in said piston and extending through the leading end thereof; a cutting head fixedly mounted on one end of said shaft adjacent the leading end of said piston; drive means for applying torque to said shaft; and hydraulic conduit means communicating with said expansible chamber for introducing a working fluid therein to thereby axially displace said piston in said hollow body; said working fluid being maintained under a predetermined positive pressure to advance said cutting head with a constant cutting attack on said pipe.
 12. A drilling assembly as defined in claim 11 wherein said one end of said tubular member extends in a plane oblique relative to the longitudinal axis of said tubular member. 